[TheAdamAndChe]

For low volume, manual purchases, Robinhood is comission-free. If you want to make a bot and need an API, there will be fees.

[panarky]

Is it really free or is there a bid-ask spread?

For example, if you buy 1 BTC and then immediately sell it, will you get the same number of dollars back?

[iav]

No market anywhere can offer that